Re: Query optimizer tells me to build an access path that alreadyexists

That's true too!

Clare

----- Original Message -----
From: <Jderham2@xxxxxx>
To: <midrange-l@xxxxxxxxxxxx>
Sent: Thursday, March 25, 2004 9:42 AM
Subject: Re: Query optimizer tells me to build an access path that
alreadyexists


> In a message dated 3/25/2004 3:54:46 AM Eastern Standard Time,
> Clare.Holtham@xxxxxxxxxxxxxx writes:
> > That's one of the indexes you ALWAYS want to build. The Optimizer may
well
> > use it for statistics (data skew). Or it may want to use an index from
index
> > access method or whatever.
> > Or do you mean you have already created the index? That can happen too.
When
> > the optimizer looks for an index, it may use different criteria or time
out
> > before it gets to the right one. These rules are different depending
which
> > version of the OS/400 you have. Sometimes it searches fifo, sometimes
the
> > other way, etc.
> > If the file is really huge you could also try creating an EVA index.
> > If you are on V5R2 there are now two different SQL Optimizers with
different
> > rules, and a new statistics gatherer.
> > If you're in the US, I believe IBM do workshops on this subject....
> >
> > cheers,
> >
> > Clare
> >
> > Clare Holtham
> > Director, Small Blue Ltd - Archiving for BPCS
> > Web: www.smallblue.co.uk
> > IBM Certified AS/400 Systems Professional
> Rumor has it that if you create the index with SQL rather then with DDS
that
> the SQL will like it more better.
> Jack D.
>
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